1231 (POD) Ogedei Khan is killed by a group of unknown assassins while walking in his garden. Subutai, a brilliant Mongol general, leading the invasion of the Song dynasty is also killed. 1232 Chagatai Khan becomes Great Khan of the Mongol Empire. 1234 Chagatai Khan declares that he will decide the next ruler of the Mongol Empire. This causes a split in the Mongol Empire, with the Chagatia Khanate facing off against the Great Khanate. Many generals and important leaders decide to remain neutral in what they seem to think could only lead to war.